<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<img src="images/水母.jpg" id="水母">
<script type="text/javascript">
var img=document.getElementById("水母");
img.onclick=function(){
	alert("这是一只水母");
}
</script>
<img src="images/Koala.jpg" onclick='alert("一只考拉")'>
</body>
</html>